Anode structure for copper electrowinning

ABSTRACT

An electrode for use in producing copper in either a conventional electrowinning cell or the direct electrowinning cell is provided. The electrode includes a hanger bar and an electrode body coupled with the hanger bar. The electrode body includes at least one conductor rod having a core and an outer layer surrounding the core and a substrate coupled with the conductor rod.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation of U.S. patentapplication Ser. No. 13/248,244 entitled, “ANODE STRUCTURE FOR COPPERELECTROWINNING” and filed on Sep. 29, 2011. The '244 Application claimspriority to and is a continuation of U.S. patent application Ser. No.12/432,473 entitled, “ANODE STRUCTURE FOR COPPER ELECTROWINNING” whichwas filed on Apr. 29, 2009, now U.S. Pat. No. 8,038,855 issued Oct. 18,2011. All the aforementioned applications are hereby incorporated byreference in their entirety.

FIELD OF THE INVENTION

The present invention generally relates to an apparatus for producingcopper using electrowinning, and relates more specifically to anelectrode apparatus for use in an electrowinning cell.

BACKGROUND

Efficiency and cost-effectiveness of copper electrowinning is, and for along time has been, important to the competitiveness of the copperindustry. Research and development efforts in this area have thusfocused, at least in part, on mechanisms for decreasing the total costfor anodes used in copper electrowinning, which directly impact thecost-effectiveness of the electrowinning process.

One type of anode employed in an electrowinning operation typicallycomprises a lead or a lead alloy, such as, for example, Pb—Sn—Ca. Onesignificant disadvantage of using such anodes is lead contamination ofthe copper cathodes. Specifically, during the electrowinning operation,small amounts of lead are released from the surface of the anode andultimately cause the generation of undesirable sediments, sludges,particulates suspended in the electrolyte, other corrosion products, orother physical degradation products in the electrochemical cell andcontamination of the copper product. Another disadvantage of using leadanodes in conventional electrowinning processes is the need to addcobalt sulfate to the copper electrolyte to help stabilize lead-basedanodes for at least one of control of surface corrosion characteristicsof the anode, control of formation of lead oxide, and/or prevention ofdeleterious effects of manganese in the system. Improvements are neededin the materials used for anodes useful for electrochemical reactions,as well as in the construction of the anodes.

SUMMARY

Accordingly, in various embodiments, the present invention provides anew design for an anode structure for use in electrowinning cells. In anaspect of an exemplary embodiment, the present invention provides ananode for an electrowinning cell that accommodates flow-through anodesand conventional cathodes. This allows for the production of highquality copper from copper-containing solutions using either aconventional electrowinning process or a direct electrowinning process.

In accordance with various embodiments, the present invention providesan electrode for producing copper in an electrowinning cell. Theelectrode includes a hanger bar and an electrode body including at leastone conductor rod and a substrate, a connection coupling the hanger barand the at least one conductor rod, and a seal isolating the connection.In an exemplary embodiment, the at least one conductor rod has an innercore and an outer layer surrounding a portion of the inner core. In anexemplary embodiment, at least one perforated substrate can be coupledto the at least one conductor rod. The present invention offerssignificant economic benefits in manufacturing and/or electrode lifetimeas compared to prior art electrodes without sacrificing functionality.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.The present invention will become more fully understood from thedetailed description and the accompanying drawings wherein:

FIG. 1 is a flow chart illustrating a process of metal value recovery,according to various embodiments of the present invention;

FIG. 2 is a cross sectional view illustrating an electrowinning cell, inaccordance with various embodiments of the present invention;

FIG. 3 is a prospective view illustrating a flow-through electrowinningcell, in accordance with an exemplary embodiment of the presentinvention;

FIG. 4 is a prospective view illustrating a flow-through electrowinningcell, in accordance with an exemplary embodiment of the presentinvention;

FIG. 5 is a prospective view illustrating a flow-through electrowinningcell, in accordance with an exemplary embodiment of the presentinvention;

FIG. 6 is a prospective view strafing a flow-through anode, inaccordance with various embodiments of the present invention;

FIG. 7 is an exploded prospective view of the flow-through anodeillustrated in FIG. 6, in accordance with various embodiments of thepresent invention;

FIG. 8A is a cross-sectional view of a conductor rod taken along line7-7 of FIG. 7, in accordance with an exemplary embodiment of the presentinvention;

FIG. 8B is a cross-sectional view of a conductor rod taken along line7-7 of FIG. 7, in accordance with an exemplary embodiment of the presentinvention;

FIG. 9 is a front exploded view illustrating a hanger bar and a portionof a plurality of conductor rods, in accordance with various embodimentsof the present invention;

FIG. 10 is an enlarged view of the portion highlighted in FIG. 9, inaccordance with various embodiments of the present invention;

FIG. 11A is a partial cross-sectional view taken along line 10-10 ofFIG. 10, in accordance with an exemplary embodiment of the presentinvention; and

FIG. 11B is a partial cross-sectional view taken along line 10-10 ofFIG. 10, in accordance with an exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present invention, its applications, or its uses.It should be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.The description of specific examples indicated in various embodiments ofthe present invention are intended for purposes of illustration only andare not intended to limit the scope of the invention disclosed herein.Moreover, recitation of multiple embodiments having stated features isnot intended to exclude other embodiments having additional features orother embodiments incorporating different combinations of the statedfeatures.

Various embodiments of the present invention are an improvement to aconventional electrode for an electrolytic cell. The present inventionexhibits significant advancements over prior art apparatus, enablessignificant improvements in copper product quality and processefficiency, and/or provides economic benefits. Moreover, existing copperrecovery processes that utilize lead-based anodes or conventionaltitanium anodes in conventional electrowinning apparatus may, in manyinstances, be retrofitted to exploit the many commercial benefits thatthe present invention can provide.

An electrowinning cell as described herein may be configured for theextraction of a variety of metal values. In the case of electrowinning,a current is passed through an anode through the electrolyte solution ormetal-bearing solution containing the metal value so that the metalvalue is extracted as it is deposited in an electroplating process ontothe cathode. In general, electrowinning metal values can include, butare not limited to, copper, gold, silver, zinc, nickel, chromium,cobalt, manganese, rare earth metals, and alkaline metals. Althoughvarious examples included in this disclosure discuss the use of an anodein the electrowinning of copper, the anode described herein, inaccordance to the present invention, may be used in the electrowinningof any metal value.

Referring to FIG. 1 in accordance with various aspects of the presentinvention, a metal-bearing material 12 is provided for processing inaccordance with metal recovery process 10. Metal-bearing material 12 maybe an ore, a concentrate, or any other material from which metal valuesmay be recovered. Metal values such as, for example, copper, gold,silver, zinc, platinum group metals, nickel, cobalt, molybdenum,rhenium, uranium, rare earth metals, and the like may be recovered frommetal-bearing material 12 in accordance with various embodiments of thepresent invention. Various aspects and embodiments of the presentinvention, however, prove especially advantageous in connection with therecovery of copper from copper sulfide ores, such as, for example,chalcopyrite (CuFeS₂), chalcocite (Cu₂S), bornite (Cu₅FeS₄), covellite(CuS), enargite (Cu₃AsS₄), digenite (Cu₉S₅), mixtures thereof and/orconcentrates thereof. In addition, various aspects and embodiments ofthe present invention also prove advantageous in connection with therecovery of copper from copper oxide ores and/or concentrates thereof.Still further, various aspects and embodiments of the present inventionprove advantageous in the recovery of any of the electrowinning metals,as listed herein, such as for example cobalt or zinc, from ores and/orconcentrates thereof. Thus, in various embodiments, metal-bearingmaterial 12 is a copper ore or concentrate, and in an exemplaryembodiment, metal-bearing material 12 is a copper sulfide ore or acopper oxide ore, mixture thereof, or concentrates thereof.

In various embodiments, processed metal-bearing material 15 may comprisemetal-bearing material 12 prepared for metal recovery process 10 in anymanner that enables the conditions of processed metal-bearing material13 to be suitable for a chosen processing method, as such conditions mayaffect the overall effectiveness and efficiency of processingoperations. Desired composition and component concentration parametersmay be achieved through a variety of chemical and/or physical processingstages, the choice of which will depend upon the operating parameters ofthe chosen processing scheme, equipment cost and materialspecifications. For example, metal-bearing material 12 may undergocomminution, flotation, blending, and/or slurry formation, as well aschemical and/or physical conditioning to produce processed metal-bearingmaterial 13. In an exemplary embodiment, processed metal-bearingmaterial 13 is a concentrate.

With continued reference to FIG. 1, after metal-bearing material 12 hasbeen suitably prepared, processed metal-bearing material 13 is subjectedto reactive processing step 14 to put a metal value or metal values inprocessed metal-bearing material 13 in a condition for later metalrecovery steps, namely metal recovery 18. For example, exemplarysuitable processes include reactive processes that tend to liberate thedesired metal value or metal values from the metal-bearing material 12.

In accordance with an exemplary embodiment of the present invention,reactive processing step 14 may comprise leaching. Leaching can be anymethod, process, or system that enables a metal value to be leached fromprocessed metal-bearing material 13. Typically, leaching utilizes acidto leach a metal value from processed metal-bearing material 13. Forexample, leaching can employ a leaching apparatus such as for example, aheap leach, a vat leach, a tank leach, a pad leach, a leach vessel orany other leaching technology useful for leaching a metal value fromprocessed metal-bearing material 13.

In accordance with various embodiments, leaching may be conducted at anysuitable pressure, temperature, and/or oxygen content. Leaching canemploy one of a high temperature, a medium temperature, or a lowtemperature, combined with one of high pressure, or atmosphericpressure. Leaching may utilize conventional atmospheric or pressureleaching, for example but not limited to, low, medium or hightemperature pressure leaching. As used herein, the term “pressureleaching” refers to a metal recovery process in which material iscontacted with an acidic solution and oxygen under conditions ofelevated temperature and pressure. Medium or high temperature pressureleaching processes for chalcopyrite are generally thought of as thoseprocesses operating at temperatures from about 120° C. to about 190° C.or up to about 250° C. In accordance with various embodiments of thepresent invention, reactive processing step 14 may comprise any type ofreactive process to put a metal value or values in processedmetal-bearing material 13 in a condition to be subjected to later metalrecovery steps.

In various embodiments, reactive processing step 14 provides ametal-bearing slurry 15 for conditioning 16. In various embodiments,conditioning 16 can be, for example, but is not limited to, a solidliquid phase separation step, an additional leach step, a pH adjustmentstep, a dilution step, a concentration step, a metal precipitation step,a filtering step, a settling step, and the like, as well as combinationsthereof. In an exemplary embodiment, conditioning 16 can be a solidliquid phase separation step configured to yield a metal-bearingsolution 17 and a metal-bearing solid.

In other various embodiments, conditioning 16 may be one or moreleaching steps. For example, conditioning 16 may be any method, process,or system that further prepares metal-bearing material 12 for recovery.In various embodiments, conditioning 16 utilizes acid to leach a metalvalue from a metal-bearing material 12. For example, conditioning 16 mayemploy a leaching apparatus such as for example, a heap leach, a vatleach, a tank leach, a pad leach, a leach vessel or any other leachingtechnology useful for leaching a metal value from a metal-bearingmaterial 12.

In accordance with various embodiments, conditioning 16 may be a leachprocess conducted at any suitable pressure, temperature, and/or oxygencontent. In such embodiments, conditioning 16 may employ one of a hightemperature, a medium temperature, or a low temperature, combined withone of high pressure, or atmospheric pressure. Conditioning 16 mayutilize conventional atmospheric or pressure leaching, for example butnot limited to, low, medium or high temperature pressure leaching.Medium or high temperature pressure leaching processes for chalcopyriteare generally thought of as those processes operating at temperaturesfrom about 120° to about 190° C. or up to about 250° C.

In various embodiments, conditioning 16 may comprise dilution, settling,filtration, solution/solvent extraction, ion exchange, pH adjustment,chemical adjustment, purification, concentration, screening, and sizeseparation. In various embodiments, conditioning 16 is a hightemperature, high pressure leach. In other embodiments, conditioning 16is an atmospheric leach. In further embodiments, conditioning 16 is asolid liquid phase separation. In still further embodiments,conditioning 16 is a settling/filtration step. In various embodiments,conditioning 16 produces metal-bearing solution 17.

In various embodiments, metal-bearing solution 17 may be subjected tometal recovery 18 to yield metal value 20. In exemplary embodiments,metal recovery 18 can comprise electrowinning metal-bearing solution 17to yield recovered metal value 20 as a cathode. In one exemplaryembodiment, metal recovery 18 may be configured to employ conventionalelectrowinning processes and include a solvent extraction step, an ionexchange step, an ion selective membrane, a solution recirculation step,and/or a concentration step. In one preferred embodiment, metal recovery18 may be configured to subject metal-bearing solution 17 to a solventextraction step to yield a rich electrolyte solution, which may besubject to an electrowinning circuit to recover a desired metal value20. In another exemplary embodiment, metal recovery 18 may be configuredto employ direct electrowinning processes without the use of a solventextraction step, an ion exchange step, an ion selective membrane, asolution recirculation step, and/or a concentration step. In anotherpreferred embodiment, metal recovery 18 may be configured to feedmetal-bearing solution 17 directly into an electrowinning circuit torecover a desired metal value 20. In an especially preferred embodiment,metal value 20 is copper.

For the sake of convenience and a broad understanding of the presentinvention, an electrowinning circuit useful in connection with variousembodiments of the present invention may comprise an electrowinningcircuit, constructed and configured to operate in a conventional manner.The electrowinning circuit may include a plurality of electrowinningcells, each cell may be constructed as an elongated rectangular tank orvessel containing alternating cathodes and anodes, arrangedperpendicular to the long axis of the tank. A metal-bearing solution maybe provided to the tank, for example at one end, to flow perpendicularto the plane of the parallel anodes and cathodes. With the applicationof current from a power supply, a metal value, such as for example,copper, can be deposited at the cathodes, and water can be electrolyzedto form oxygen and protons at the anodes.

With initial reference to FIG. 2, an exemplary electrowinning cell 100is illustrated in accordance with various embodiments of the presentinvention. Electrowinning cell 100 comprises vessel 102 configured tohold a series of electrodes 104. Power supply (not pictured) can becoupled to series of electrodes 104. In various embodiments, series ofelectrodes 104 can comprise a plurality of alternating anodes 112 andcathodes 110. As understood by one of ordinary skill in the art, anynumber of anodes 112 and/or cathodes 110 may be utilized. In addition anelectrowinning circuit may comprise an individual electrowinning cell100 or a plurality of electrowinning cells 100 connected in series or inparallel.

Typically, metal-bearing electrolytic solution 107 enters through entryport 106 at one end and flows through cell 100 (and thus past electrodes104), during which a metal value is electrowon from metal-bearingelectrolytic solution 107 onto cathode 110. An active surface or area ofeach of the series of electrodes 104 is the portion of each of theseries of electrodes 104 that is immersed in metal-bearing electrolyticsolution 107 up to solution fill level 116. In an exemplary embodiment,metal-bearing electrolytic solution 107 is metal-bearing solution 17. Ina preferred embodiment, metal-bearing electrolytic solution 107comprises at least copper. Lean electrolyte (metal-bearing electrolyticsolution 107 having a reduced concentration of metal value) exits atexit port 108 of cell 100 at a distal end. In accordance with one aspectof an exemplary embodiment of the present invention, at least a portionof lean electrolyte may be returned to cell 100. In another aspect of anexemplary embodiment, at least a portion of lean electrolyte can bereturned to at least one of reactive processing 14 and conditioning 16.

The general process of copper electrowinning, wherein copper is platedfrom a copper electrolyte, such as for example metal-bearingelectrolytic solution 107, to a substantially pure cathode in an aqueouselectrolyte is believed to occur by the following reactions:

Cathode Reaction:

Cu²⁺+SO₄ ²⁻+2e ⁻→Cu⁰+SO₄ ²⁻ (E⁰=+0.340 V)

Anode Reaction:

H₂O→½O₂+2H⁺+2e ⁻ (E⁰=+1.230 V)

Overall Cell Reaction:

Cu²⁺+SO₄ ²⁻+H₂O→Cu⁰+2H⁺+SO₄ ²⁻+½O₂ (E⁰=+0.890 V)

Conventional copper electrowinning operations use either a copperstarter sheet or a stainless steel “blank” or titanium “blank” as thecathode 110. In accordance with one aspect of an exemplary embodiment ofthe present invention, the cathode 110 is configured as a metal sheet.The cathode 110 may be formed of copper, copper alloy, stainless steel,titanium, or another metal or combination of metals, alloys, and/orother suitable materials. As illustrated in FIG. 2 and as is generallywell known in the art, cathode 110 is typically suspended from the topof electrochemical cell 100 such that a portion of cathode 110 isimmersed below solution fill level 116 in metal-bearing electrolyticsolution 107, as discussed above. This active surface is the portion ofcathode 110 onto which a metal value, such as copper, is plated duringelectrowinning.

In general, electrowinning chemistry and electrowinning apparatus forcopper value recovery are known in the art. As with conventionalelectrowinning cells, the rate at which direct current can be passedthrough cell 100 is effectively limited by the rate at which copper ionscan pass from the copper-bearing solution to the cathode surface. Thisrate, also known as the limiting current density, is a function offactors such as copper concentration, diffusion coefficient of copper,cell configuration, and level of agitation of the aqueous copper-bearingsolution. Conventional electrowinning operations typically operate atcurrent densities in the range of about 220 to about 380 Amps per squaremeter (“A/m²”) or of about 20 Amps per square foot (“A/ft²”) of activecathode, and more typically in the range of about 300 A/m² and about 350A/m² or of about 28 A/ft² and about 32 A/ft². Use of an electrolyticsolution flow system, which can provide additional electrolytecirculation and/or air injection into an electrochemical cell 100, canallow for higher current densities to be achieved.

In accordance with an exemplary embodiment of the present invention,overall cell voltage in a range of from about 0.75 Volts (“V”) to about3.0 V can be achieved, preferably less than about 1.9 V, and morepreferably less than about 1.7 V. The overall cell voltage achievablecan be dependent upon a number of factors, including spacing of theseries of electrodes 104, the configuration and materials ofconstruction of the series of electrodes 104, acid concentration andmetal value concentration in the electrolytic solution 107, currentdensity, electrolytic solution 107 temperature, electrolytic solution107 conductivity, and, to a smaller extent, the nature and amount of anyadditives to the electrowinning process (such as, for example,flocculants, smoothing agents, and/or surfactants.

Generally speaking, as the operating current density in theelectrochemical cell 100 increases, the metal value plating rate ontocathode 110 increases. Stated another way, as the operating currentdensity increases, more cathode 110 of the metal value, for example,copper, is produced for a given time period on cathode active surfacearea than when a lower operating current density is achieved.Alternatively, by increasing the operating current density, the sameamount of the metal value may be produced in a given time period, butwith less active cathode surface area (i.e., fewer or smaller cathodes110, which corresponds to lower capital equipment costs and loweroperating costs).

In accordance with one aspect of an exemplary embodiment of the presentinvention, the temperature of metal-bearing electrolytic solution 107 inelectrowinning cell 100 is maintained at from about 40° F. to about 150°F. In accordance with one preferred embodiment, metal-bearingelectrolytic solution 107 is maintained at a temperature of from about90° F. to about 140° F. Higher temperatures may, however, beadvantageously employed. For example, in direct electrowinningoperations, temperatures higher than 140° F. may be utilized.Alternatively, in certain applications, lower temperatures mayadvantageously employed. For example, when direct electrowinning ofdilute copper-containing solutions is desired, temperatures below 85° F.may be utilized.

The operating temperature of metal-bearing electrolytic solution 107 inelectrowinning cell 100 may be controlled through any one or more of avariety of means well known in the art, including, for example, heatexchange, an immersion heating element, an in-line heating device (e.g.,a heat exchanger), or the like, preferably coupled with one or morefeedback temperature control means for efficient process control.

In accordance with an exemplary embodiment of the present invention, theacid concentration in the metal-bearing electrolytic solution 107 forelectrowinning may be maintained at a level of from about 5 grams toabout 250 grams of acid per liter of metal-bearing electrolytic solution107. In accordance with one aspect of a preferred embodiment of thepresent invention, the acid concentration in the metal-bearingelectrolytic solution 107 is advantageously maintained at a level offrom about 150 grams to about 205 grams of acid per liter ofmetal-bearing electrolytic solution 107, depending upon the upstreamprocess.

In accordance with an exemplary embodiment of the present invention, thecopper concentration in metal-bearing electrolytic solution 107 forelectrowinning is advantageously maintained at a level of from about 5grams of copper per liter (“g/L”) to about 40 g/L of metal-bearingelectrolytic solution 107. Preferably, the copper concentration ismaintained at a level of from about 10 g/L to about 35 g/L ofmetal-bearing electrolytic solution 107. However, various aspects of thepresent invention may be beneficially applied to processes employingcopper concentrations above and/or below these levels, with lower copperconcentration levels of from about 0.5 g/L to about 5 g/L and uppercopper concentration levels of from about 40 g/L to about 50 g/L beingapplied in some cases.

While various configurations and combinations of anodes 112 and cathodes110 in the electrochemical cell 100 may be used effectively inconnection with various embodiments of the present invention, aflow-through anode can be used, and electrolytic solution flow systemcan include an electrolyte flow manifold capable of maintainingsatisfactory flow and circulation of electrolyte within theelectrowinning cell.

Generally speaking, any electrolytic solution pumping, circulation, oragitation system capable of maintaining satisfactory flow andcirculation of metal-bearing electrolytic solution 107 between theseries of electrodes 104 in an electrowinning cell 100 such that theprocess specifications described herein are practicable and may be usedin accordance with various embodiments of the present invention.

In accordance with an exemplary embodiment of the present invention, themetal-bearing electrolytic solution 107 flow rate is maintained at alevel of from about 0.05 gallons per minute per square foot of activecathode 110 to about 30 gallons per minute per square foot of activecathode 110. Preferably, the metal-bearing electrolytic solution 107flow rate is maintained at a level of from about 0.1 gallons per minuteper square foot of active cathode 110 to about 0.75 gallons per minuteper square foot of active cathode 110. It should be recognized that theoptimal operable metal-bearing electrolytic solution 107 flow rateuseful in accordance with the present invention will depend upon thespecific configuration of the process apparatus as well as theelectrolyte chemistry employed, and thus flow rates in excess of about30 gallons per minute per square foot of active cathode 110 or less thanabout 0.05 gallons per minute per square foot of active cathode 110 maybe optimal in accordance with various embodiments of the presentinvention. Moreover, metal-bearing electrolytic solution 107 movementwithin electrowinning cell 100 may be augmented by agitation, such asthrough the use of mechanical agitation and/or gas/solution injectiondevices, to enhance mass transfer.

Referring now to FIG. 3, an electrochemical cell in accordance withvarious aspects of an exemplary embodiment of the present invention isillustrated. Electrochemical cell 300 generally comprises vessel 302configured to hold at least one anode 304, at least one cathode 306,electrolyte injection inlet 308, and outlet port 310. Although an angledelectrolytic solution injection inlet configuration is illustrated inFIG. 3 for purposes of reference, any number of configurations of anelectrolytic solution injection inlet 308 may be possible. Electrolyteinjection inlet 308 preferably may be configured to substantiallydistribute flow of metal-bearing electrolytic solution 107 evenly acrossthe active surfaces of at least one anode 304 and at least one cathode306.

Referring now to FIG. 4, an electrochemical cell in accordance withvarious aspects of an exemplary embodiment of the present invention isillustrated. Electrochemical cell 400 generally comprises vessel 402configured to hold at least one anode 404, at least one cathode 406, anddistributor plate 408 comprising a plurality of injection holes 410.Although an approximately horizontal electrolytic solution injectionconfiguration is illustrated in FIG. 4 for purposes of reference, anynumber of configurations of differently directed and spaced injectionholes 410 may be possible. For example, although injection holes 410illustrated in FIG. 4 are approximately parallel to one another andsimilarly directed, configurations comprising a plurality of opposinginjection streams or intersecting injection streams may be beneficial inaccordance with various embodiments of the present invention.Preferably, distributor plate 408 can be configured to substantiallydistribute flow of metal-bearing electrolytic solution 107 evenly acrossthe active surfaces of at least one anode 404 and at least one cathode406.

Injection velocity of the metal-bearing electrolytic solution 107 intoan electrochemical cell may be varied by changing the size and/orgeometry of the holes or slots through which electrolyte enters theelectrochemical cell 400. For example, with reference to FIG. 4 whereinelectrolytic solution 107 feed is sent through distributor plate 403configured having a plurality of injection holes 410, if the diameter ofinjection holes 410 is decreased, the injection velocity of theelectrolytic solution 107 is increased, resulting in, among otherthings, increased agitation of the electrolytic solution 107. Moreover,the angle of injection of electrolytic solution 107 into electrochemicalcell 400 relative to the cell walls and the electrodes, such as anode404 and cathode 406, may be configured in any way desired, through anynumber of cell walls.

Referring now to FIG. 5, an electrochemical cell in accordance withvarious aspects of an exemplary embodiment of the present invention isillustrated. Electrochemical cell 500 generally comprises vessel 502configured to hold at least one anode 504, at least one cathode 506, andelectrolyte flow manifold 508 comprising a plurality of injection holes510 distributed throughout at least a portion of vessel 502. As can beseen in FIG. 5, electrolytic solution flow manifold 508 is a “floor mat”type manifold that is located on the floor of vessel 502. Flow manifold508 preferably is configured to substantially distribute flow ofmetal-bearing electrolytic solution 107 evenly across the activesurfaces of at least one anode 504 and at least one cathode 506.

In accordance with various embodiments of the present invention,exemplary electrochemical cells 300, 400, and 500 comprise examples ofapparatus useful for implementation of an electrowinning step in anelectrowinning cell 100, as illustrated in FIG. 2. These and otherexemplary aspects are discussed in greater detail herein below.

In accordance with exemplary embodiments of the present invention, aflow-through anode, such as anodes 304, 404, and 504 illustrated inFIGS. 3-5, can be incorporated into any of exemplary cells 100, 302, 402and 502 illustrated in FIGS. 1 and 3-5. Likewise, in accordance withexemplary embodiments of the present invention, a flow-through cathode,such as cathode 306, 406, and 506 illustrated in FIGS. 3-5, can beincorporated into any of exemplary cells 100, 302, 402 and 502illustrated in FIGS. 1 and 3-5.

Referring now to FIGS. 6-11, an electrode for an electrolytic cell isillustrated in accordance with various embodiments of the presentinvention. An exemplary embodiment of the electrode can be aflow-through anode 600 which will be discussed in detail. It should beunderstood that the anode 600 discussed below in detail can beincorporated into exemplary cells 300, 400, and 500 as anodes 304, 404,and 504 respectively or into exemplary cell 100 as anodes 112.

In accordance with various embodiments, anode 600 can comprise hangerbar 602 and at least one conductor rod 612. Anode 600 may comprisehanger bar 602 and anode body 604. Anode body 604 may comprise at leastone conductor rod 612 and at least one substrate 614 coupled to at leastone conductor rod 612. In accordance with an exemplary embodiment,hanger bar 602 is made from copper. In accordance with an exemplaryembodiment, anode body 604 is suspended from hanger bar 602. Preferably,during use, substantially all of anode body 604 is immersed in anelectrolyte solution (i.e., below electrolyte fill level 116, asillustrated in FIG. 2).

In accordance with an exemplary embodiment, anode body 604 comprisessubstrate 614, as illustrated in FIGS. 6 and 7. Preferably, inaccordance with an exemplary embodiment, substrate 614 comprises a meshscreen, perforated sheet or an expanded metal sheet. For example inconstructing substrate 614, an expanded sheet may be made by puttingslits through a metal sheet then pulling the metal sheet from all sidesto create an expanded sheet having a plurality of substantiallydiamond-shaped holes. Substrate 614 may be constructed of any conductivematerial, for example, those as described herein. In variousembodiments, substrate 614 comprises a valve metal or a combination ofvalve metals or alloys comprising at least one valve metal. In anexemplary embodiment, substrate 614 comprises titanium.

In other embodiments, anode body 604 may comprise substrate 614configured in the form of a mesh-like substrate. In an exemplaryembodiment, substrate 614 comprises a woven wire screen with about a100×100 strand per square inch to about a 10×10 strand per square inch,preferably from about an 80×80 strand per square inch to about a 30×30strand per square inch, and more preferably about a 60×60 strand persquare inch to about a 40×40 strand per square inch. However, othervarious rectangular and irregular geometric mesh configurations may beused. In various embodiments, substrate 614 may be somewhat more porous,for example, a strand every square inch. Any strand pitch may be usedfor construction of substrate 614. In various embodiments, substrate 614uses an irregular pattern in which there is not a consistent pitch fromside to side.

In accordance with various embodiments, substrate 614 may be fastened toconductor rods 612, and such fastening methods are well known in the artand may include, for example, welding, adhesives, braided wire,fasteners, staples, and the like. Any means now known or hereafterdeveloped in the future that may hold substrate 614 to rods 612 may beused as long as a portion of the substrate 614 is in electricalconductive contact to at least one of the conductor rods 612. Inaccordance with one exemplary embodiment, substrate 614 may be welded toconductor rods 612.

Conductor rods 612, which are coupled to hanger bar 602, can be of anynumber. In an aspect of the present invention, the number of conductorrods can be from about 4 to about 12, or from about 6 to about 8, orabout 6, or about 8. In various embodiments, at least two of substrate614 can be coupled to either side of conductor rods 612, then the edgesof the at least two of substrate 614 can be coupled together. In such aconfiguration, the at least two of substrate 614 create an envelopearound a plurality of conductor rods 612. The coupling of the edges ofthe at least two of substrate 614 can increase rigidity and/or increaselifetime of anode body 604. In addition, the coupling of the edges ofthe at least two of substrate 614 can improve the coupling of substrate614 to conductor rods 612 and/or improve conductivity of anode body 604.

In accordance with another aspect of an exemplary embodiment of thepresent invention, substrate 614 may comprise any electrochemicallyactive coating on a surface of substrate 614. Exemplary coatings includethose provided from platinum, ruthenium, iridium, or other Group VIIImetals, Group VIII metal oxides, or compounds comprising Group VIIImetals, and oxides and compounds of titanium, molybdenum, tantalum,and/or mixtures, alloys and combinations thereof. A mixture of tantalumoxide and iridium oxide can be used as an electrochemically activecoating on substrate 614. Preferably, in accordance with one exemplaryembodiment, substrate 614 comprises a titanium mesh with a coatingcomprised of a mixture of iridium oxide and tantalum oxide.

In accordance with various embodiments, conductor rod 612 contains core802 and outer layer 804, as illustrated in FIG. 8A, which is across-sectional view of conductor rod taken along line 7-7 of FIG. 7.Outer layer 804 can cover essentially the entirety of core 802 belowhanger bar 602. Core 802 comprises a conductive material, for example,but not limited to, copper, copper alloy, aluminum, copper aluminumalloy, stainless steel, titanium, gold, combinations thereof, or anyother electrically-conductive materials suitable for core 802.

Outer layer 804 can be any conductive metal, such as, for example, avalve metal. Outer layer 804 can be formed of one of the so-called valvemetals, including titanium, tantalum, zirconium, and niobium. Forexample, titanium may be alloyed with nickel, cobalt, iron, manganese,or copper can form a suitable outer layer 804. In an exemplaryembodiment, outer layer 804 comprises titanium because, among otherthings, titanium is rugged and corrosion-resistant and in that regardcan extend the lifetime of anode 600. In accordance with an exemplaryembodiment, outer layer 804 can be made from titanium and may be coldrolled onto core 802 or clad thereon.

In accordance with an exemplary embodiment, conductor rod 612 includesfirst end 806 and second end 808 which is distal to first end 806. Firstend 806 includes attachment portion 810. Attachment portion 810 includesexposed core 802 and does not include outer layer 804 of conductor rod612. In an exemplary embodiment, if core 806 has outer layer 804 thathas been cold-rolled over the surface of core 804, a portion of outerlayer 804 may be cut near first end 806 to create attachment portion810.

Second end 808 of conductor rod 612 contains cap 814. Cap 814 fitswithin removed portion 816 of core 802. Removed portion 816 of core 802may be removed by any suitable method. In accordance with an exemplaryembodiment, removed portion 816 of core 802 is removed by contacting itwith an acid. As will be apparent to those skilled in the art, cap 814may comprise a myriad of different configurations as compared to that inFIG. 8A. For example, cap 814 may be a disc, having a diameter equal tothe outer diameter of conductor rod 612 and attached to the end ofconductor rod 612 using means known to those skilled in the art orhereafter developed, such as for example, an adhesive, welding,fasteners, combinations thereof, and the like. Other configurations forcap 814 can include an edge that is greater than the diameter ofconductor rod 612. In such configurations, cap 814 can be fastened usingthreads, forced on, crimped, adhesives, welding, fasteners, combinationsthereof, and the like. Any configuration of cap 814 known to thoseskilled in the art or developed in the future may be used at second end808 of conductor rod 612. Use of cap 814 is advantageous to prevent acidfrom eating away core 802 of conductor rod 612 when anode 600 is used inelectrowinning applications.

In accordance with another aspect of an exemplary embodiment of thepresent invention, conductor rod 612 may also optionally comprise anyelectrochemically active coating. Exemplary coatings include thoseprovided from platinum, ruthenium, iridium, or other Group VIII metals,Group VIII metal oxides, or compounds comprising Group VIII metals, andoxides and compounds of titanium, molybdenum, tantalum, and/or mixtures,alloys and combinations thereof. A mixture of tantalum oxide and iridiumoxide can be used as an electrochemically active coating on conductorrod 612.

In accordance with various embodiments, conductor rod 612 contains core802 and outer layer 804, as illustrated in FIG. 8B, which is across-sectional view of conductor rod taken along line 7-7 of FIG. 7.Core 802 and outer layer 804 comprise any materials discussed herein. Inaccordance with an exemplary embodiment, core 802 can comprise copperand outer layer 804 can be made from titanium and may be cold rolledonto core 602 or dad thereon.

In accordance with an exemplary embodiment, conductor rod 612 includesfirst end 806 and second end 808 which is distal to first end. First end606 includes attachment portion 810. Attachment portion 810 includesexposed core 802 and does not include outer layer 804 of conductor rod612.

In an exemplary embodiment, circumferential groove 812 may be inscribedin core 802 adjacent to outer layer 804. More specifically, thecircumferential groove 812 may be machined into core 802. If core 802has outer layer 804 that has been cold-rolled over the surface of core802, a portion of outer layer 804 may be cut near first end 806 tocreate attachment portion 810. Once outer layer 804 is cut, a portion ofouter layer 804 may be removed and the cutting of outer layer 804 maycreate groove 812. In an exemplary embodiment, outer layer 804 can becold-rolled or clad onto core 802 up to groove 812. Using such a method,groove 812 may be used as a guide for rolling outer layer 804 over core802 such that a length of attachment portion 810 is essentiallyequivalent across a plurality of conductor rods 612. In an exemplaryembodiment, grooves can be configured to hold a seal member (not shown)for example a synthetic rubber O-ring type seal, or a fluoropolymerelastomer O-ring type seal.

Referring now to FIGS. 9 and 10, hanger bar 602 will be discussed. Inaccordance with an exemplary embodiment, hanger bar 602 can be a“steerhead” configuration, which is configured to be positionedhorizontally in an electrowinning cell. Other configurations for hangerbar 602 may, however, be utilized, such as, for example, substantiallystraight configurations, multi-angled configurations, offsetconfigurations and the like. In accordance with an exemplary embodiment,hanger bar 602 contains an upper surface 906 and a lower surface 908. Inaccordance with an exemplary embodiment, the lower surface 908 containsa plurality of recessed holes 910 that extend within the hanger bar,upwardly along a vertical axis.

In accordance with an exemplary embodiment, at least one conductor rod612 can be coupled with hanger bar 602 and suspended therefrom, asillustrated in FIGS. 6, 9 and 10. In accordance with an exemplaryembodiment, attachment portion 810 of conductor rod 612 can be insertedinto recessed hole 910 of hanger bar 602. Preferably, in accordance withan exemplary embodiment, attachment portion 810 of conductor rod 612 ispress fit within recessed hole 910. Attachment portion 810 can beinserted such that core 802 is flush within recessed hole 910 therebyproviding for a suitable electrically conductive connection between core802 and hanger bar 602.

With reference to FIGS. 11A and 11B, connection 930 is illustrated as across sectional view along the line 10-10 of FIG. 10. Connection 930comprises one of the plurality of recessed holes 910 and attachmentportion 810 fastened in the one of the plurality of recessed holes 910.In an exemplary embodiment, connection 930 can be a press fit attachmentof attachment portion 810 into one of plurality of recessed holes 910such that attachment portion 810 is forced into one of plurality ofrecessed holes 910.

Referring now to FIGS. 11A and 11B and in accordance with an exemplaryembodiment, attachment portion 810 of conductor rod 612 is inserted intorecessed hole 910 of hanger bar 602. Preferably, in accordance with anexemplary embodiment, attachment portion 810 of conductor rod 612 ispress fit within recessed hole 910. Attachment portion 810 is insertedsuch that core 802 is flush within recessed hole 910 thereby providingfor a suitable electrically conductive connection between core 802 andhanger bar 602.

In another aspect of an exemplary embodiment, attachment portion 810 maybe tapered, making it easier to form connection 930 when meeting an endof the end of the forward end of attachment portion 810 into one ofplurality of recessed holes 910. In addition, tapering of attachmentportion 810 can be advantageous when connection 930 is a press fit sincea force is only necessary when the taper is equal to or greater than thediameter of the one of the plurality of recessed holes 910. In anexemplary embodiment, attachment portion 810 is made out of copper and,as such, may be malleable under pressure during a press fit forconnection 930. In addition, hanger bar 602 may be made of copper and,as such, may be somewhat malleable which may be advantageous in creatinga press fit for connection 930. In an exemplary embodiment, connection930 comprising attachment portion 810 and one of the plurality ofrecessed holes 610 creates an electrical conductive interface betweenhanger bar 602 and conductor rod 612.

Other attachment means may be used for connection 930, for example,threads, barbed surfaces, chamfer surfaces, lock-tight fittings, andcombinations thereof. In addition, secondary materials, such asadhesives, welds, splints, deformable members, and the like can be usedto reinforce connection 930.

With continual reference to FIGS. 11A and 11B, seal 932 is illustratedin accordance with another aspect of exemplary embodiments of thepresent invention. Seal 932 can be created during a press fit ofconnection 930 between attachment portion 810 and one of the pluralityof recessed holes 910. In an exemplary embodiment, plurality of recessedholes 910 comprises notch 934. Notch 934 can be an indentation in lowersurface 908 of hanger bar 602 having end 936 of notch 934 which issubstantially parallel to the plane of lower surface 908. Notch 934typically has a diameter which is greater than the diameter of theplurality of recessed holes 910. In an aspect of an exemplaryembodiment, a diameter of notch 934 is greater than an outer diameter ofouter surface 804 of conductor rod 612.

In accordance with another aspect of an exemplary embodiment, seal 932is at an interface of end 936 of notch 934 and forward edge 824 of outersurface 804. Forward surface 824 of outer surface 804 is essentiallyperpendicular to the length of conductor rod 612. As will be appreciatedby those skilled in the art, to optimize performance of seal 932, asurface of forward edge 824 of outer surface 804 and a surface of end936 of notch 934 should be essentially smooth and flat. If an angle isused for either the forward edge 824 of the outer surface 804 or end 936of notch 934, as will be appreciated by those skilled in the art, suchangles should be complimentary to optimize seal 932.

Seal 932 essentially isolates connection 930. For example, if anode 600is utilized in electrowinning for copper, seal 932 can isolateconnection 930 from acid fumes from the electrolytic cell. It isadvantageous to isolate connection 930 from acid fumes so that theintegrity of connection 930 is not affected by etching effects of acidfumes to the inter wall of one of the plurality of recessed holes 910and/or outer surface of attachment portion 810. In this regard, use ofseal 932 can ensure greater lifetime of anode 600. Seal 932 can includea compressible ring, a polymeric ring or grommet, or any other such sealinterfaces that are now known to those skilled in the art or hereafterdeveloped. As will be appreciated by those skilled in the art, if such aseal interface is employed between end 936 of notch 934 and leading edge824 for seal 932, it is preferred that such a seal interface impermeableto whichever solution or gas from which seal 932 is isolating connection930, or at least the seal interface does not communicate such solutionor gas into connection 930.

With reference to FIG. 118, in an exemplary embodiment, groove 812assists in press fit of connection 930 such that attachment portion 810may be deformed as it is press fit into one of plurality of recessedholes 910 and as such the deformation of attachment portion 810 may movesome material into groove 812. In an exemplary embodiment, groove 812can be configured to hold a seal member, such as, for example, asynthetic rubber O-ring type seal or a fluoropolymer elastomer O-ringtype seal.

According to various embodiments, the present invention provides methodsof making an electrode useful for electrowinning a metal value. Invarious embodiments, the method can include cladding core 802 with outerlayer 804 and exposing an attachment portion to 810. As discussedherein, outer layer 804 can be cold-rolled over core 802. In anotherexemplary embodiment of the present invention, core 802 may be dipped ina solution to create outer layer 804. Exposing attachment portion 810can include cutting a portion of outer layer 804 and removing the cutportion of outer layer 804 to expose attachment portion 810 of core 802.In various embodiments, the method can include capping an end ofconductor rod 612. The capped end is distal to attachment portion 810.In an exemplary embodiment, the method can include etching a portion ofcore 802 distal to attachment portion 810. The etching of core 802creates a portion that is removed to provide space for attachment of cap814. The method can also include welding cap 814 to conductor rod 612.In various embodiments, the method can include creating a plurality ofrecessed holes 910 in hanger bar 602. Creating a plurality of recessedholes 910 can include drilling, machining, etching, and the like. In anexemplary embodiment of the present invention, the method can includecreating a recessed notch 934 around a circumference of each of theplurality of recessed holes 910.

In various embodiments, the method can include connecting at least oneconductor rod 612 to hanger bar 602. In an exemplary embodiment, themethod can include press fitting attachment portion 810 into one ofplurality of recessed holes 910. The method can include creatingconnection 930 by mating attachment portion 810 with one of plurality ofrecessed holes 910. The method can include reinforcing connection 930and such reinforcement can include applying an adhesive, inserting ashim, welding, applying a fastener, and combinations thereof.

In an exemplary embodiment, the method can include creating seal 932.Seal 932 can be created by interfacing front surface 824 of outer layer804 with end 936 of notch 934. In an exemplary embodiment, the methodcan include isolating connection 930. Seal 932 can essentially isolateconnection 930. In various embodiments, the method can include coatingconductor rod 612 with an electrochemically active coating.

In various embodiments, the method can include attaching at least onesubstrate 614 to at least one conductor rod 614. In an exemplaryembodiment, the method can include coating at least a portion ofsubstrate 614. Attaching substrate 614 to at least one conductor rod 612can include welding, braiding, stapling, fastening, and/or combinationsthereof. In an exemplary embodiment, ent, the method can includeattaching a second substrate 614 to at least one conductor rod 612. Themethod can include coating at least a portion of substrate 614 with anelectrochemically conductive coating.

The present invention has been described above with reference to anumber of exemplary embodiments. It should be appreciated that theparticular embodiments shown and described herein are illustrative ofthe present invention and its best mode and are not intended to limit inany way the scope of the present invention as set forth in the claims.Those skilled in the art having read this disclosure will recognize thatchanges and modifications may be made to the exemplary embodimentswithout departing from the scope of the present invention. For example,various aspects and embodiments of this invention may be applied toelectrowinning of metals other than copper, such as nickel, zinc,cobalt, and others. Although certain preferred aspects of the presentinvention are described herein in terms of exemplary embodiments, suchaspects of the present invention may be achieved through any number ofsuitable means now known or hereafter devised. Accordingly, these andother changes or modifications are intended to be included within thescope of the present invention.

1. An electrode comprising: a conductor bar having a recess; a conductorrod comprising a core clad in a valve metal and an attachment portionhaving an exposed core; and wherein the conductor rod is press fit intothe recess.
 2. The electrode according to claim 1, further comprising asubstrate coupled to the conductor rod.
 3. The electrode according toclaim 1, wherein the core is selected from the group consisting ofcopper and aluminum.
 4. The electrode according to claim 1, wherein thevalve metal is titanium.
 5. The electrode according to claim 2, whereinthe substrate comprises titanium.
 6. The electrode according to claim 2,wherein the substrate comprises an electrochemically active coating. 7.The electrode according to claim 6, wherein the electrochemically activecoating comprises a mixture of tantalum oxide and iridium oxide.
 8. Theelectrode according to claim 7, wherein the substrate comprises atitanium mesh.
 9. The electrode according to claim 1, wherein theconduct bar is a hanger bar.
 10. The electrode according to claim 9,wherein the hanger bar has a steerhead configuration.
 11. The electrodeaccording to claim 1, wherein the attachment portion is tapered.
 12. Theelectrode according to claim 1, further comprising a seal disposed atthe interface of the attachment portion and the conductor bar.
 13. Theelectrode according to claim 12, wherein the seal comprises at least oneof a compressible ring, a polymeric ring and a grommet.
 14. A method forconstructing an electrode comprising: exposing a core at a first end ofa conductor rod, wherein the conductor rod comprises the core clad in avalve metal; and press fitting the first end of the conductor rod into arecess of a conductor bar.
 15. The method according to claim 14, furthercomprising coupling a substrate to the conductor rod.
 16. The methodaccording to claim 15, further comprising coating a portion of a surfaceof the substrate with an electrochemically active coating.
 17. Themethod according to claim 14, further comprising disposing a seal at thejunction between the conductor rod and the conductor bar.
 18. The methodaccording to claim 14, further comprising capping a distal end of theconductor rod.